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Does the FAA give a regulatory definition of the term "Touchdown Zone" for use within the context of landing operations?


In 14 CFR 91.175 the FAA requires—in certain cases—that pilots must be in a position to land within the "Touchdown Zone":

(c) Operation below DA/DH or MDA. Except as provided in §91.176 of this chapter, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

Is this zone explicitly defined? If so, where is the applicable definition found?


No definition is offered in 14 CFR 1.1. However, several uses or definitions of this term do exist in various FAA advisory documents. These uses or definitions are generally similar, but include variances. A few of these include:

AC 91-79A (referencing an obsolete document):

the TDZ is referred to as a point 500-3,000 ft beyond the runway threshold not to exceed the first one-third of the runway

AIM 2–1–5:

3,000 ft beyond the landing threshold or to the midpoint of the runway, whichever is less.

The Pilot Controller Glossary:

The first 3,000 ft of the runway beginning at the threshold.

Also of note, the runway touchdown zone markings on long precision runways generally extend to 3,000 ft beyond the threshold.

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    $\begingroup$ Within your question you provided three answers from legitimate referenced sources that all say pretty much the same thing. What do you find lacking in these definitions, and kind of an answer would satisfy you? $\endgroup$ – Michael Hall Sep 16 at 15:37
  • $\begingroup$ … BTW, the differences are not lost on me, but will they really affect your decision to continue or not? E.g. if the approach is into a 5000' runway will you decide that you are OK to land past the midpoint since you choose to honor the Pilot Controller Glossary definition? (because while being past both the first third and the halfway point, you are still legally within the first 3000') $\endgroup$ – Michael Hall Sep 16 at 16:45
  • $\begingroup$ @MichaelHall Note that my question is specifically in search of regulatory definitions. Those that I offered above as part of my findings to this point are all advisory at best. Other FAA guidance that was not accepted data included even greater variance, some of which may have been misquotations. Note also that the cases where this definition might be important are relatively narrow. $\endgroup$ – J Walters Sep 17 at 1:41
  • $\begingroup$ @MichaelHall My interest as a pilot is not on how to determine when a go-around is necessary: landing within an appropriate zone is not difficult. The proper definition of the term becomes especially important in the case of instructing or training. For example, I have heard assertions that pilots are required, in everyday operations, to land within a certain narrow margin near the aiming point marker; I believe these assertions are in error. I believe that the answer to my question is that there is no single, regulatory definition. $\endgroup$ – J Walters Sep 17 at 1:45
  • $\begingroup$ I follow you. In these matters I always try to put the burden of proof on those making assertions to back them up. And I agree with your last sentence, I doubt there is a regulatory definition. And I don't think we want one either. Opens pilots up to risk of a flight violation for nothing more than poor technique. (or for an intentional long landing by a small plane on a big runway that doesn't want a long taxi...) $\endgroup$ – Michael Hall Sep 17 at 20:21

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